| Paper | Title | Page |
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| MOPPD050 | Dipole Magnet Design for a Bunch Compressor | 478 |
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| The FRANZ-ARMADILLO is a Mobley type bunch compressor system at the pulsed intense neutron source FRANZ, under construction at Frankfurt University. The FRANZ-ARMADILLO compresses 9μbunches of a 150 mA, 2 MeV proton beam accelerated by a 175 MHz linac into one short pulse of 1 ns pulse length with 250 kHz repetition rate. In the bunch compressor, two homogeneous dipole magnets and two gradient dipole magnets guide theμbunches, separated by a 5 MHz RF-kicker on individual tracks. The flight path length of theμbunches are determined based on the bunch center velocity and the linac frequency for the longitudinal bunch compression. The gradient dipole magnets provide individual magnetic fields and edge focusing forces to everyμbunch. For the center trajectory, the required parameters are a magnetic field density of 509.2 mT, bending angle of 78.27 deg, and bending radius of 404.5 mm. To satisfy all specifications, field clamps, shims, and chamfer cut will be adopted. The result of the gradient dipole magnet design and the expected performance based on beam dynamics studies will be presented. | ||
| TUPPC007 | Electron Cloud Dynamics in a Gabor Space Charge Lens | 1164 |
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| Inside Gabor space charge lenses, external fields confine electrons forming a homogeneously distributed electron cloud. Its linear electric space charge field enables the focusing of high intensity heavy ion beams without aberrations. The focusing performance depends on the properties of the non-neutral plasma. In a small-scale table top experiment, different types of space charge lenses are used to characterize the collective behavior of the confined electron cloud using new non-interceptive diagnostic methods. The plasma parameters, e.g. electron temperature and density, are important to an improved understanding of loss and production mechanisms as well as the electron cloud dynamics. In this context, the evolution of instabilities caused by the enclosing fields has been investigated in detail. Experimental results will be presented and compared to numerical simulations. | ||
| THPPC003 | Development of a Broad-band Magnetic Alloy Cavity at GSI | 3275 |
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FINEMET, a Magnetic Alloy material, is often used to build a broad-band cavity for an accelerator or a storage ring. A research on the broad-band FINEMET cavity is of prime importance not only for the present accelerator facility but also for the future storage rings and synchrotron in upcoming FAIR facility alongside the GSI, Darmstadt. In several measurements, high intensity rare-isotope beams, with lower life time, are demanded at injection energy in Experimental Storage Ring (ESR) at GSI. A longitudinal beam stacking of such beams by means of using a special barrier-bucket RF cavity is found appropriate to serve this purpose*. Additionally, this cavity is supposed to provide the compressed bunches at lower energies for HITRAP, an ion-trap facility for experiments with highly charged ions, in FAIR. Several measurements are being performed, along with the theoretical analysis, to achieve the designed parameters for the planned barrier-bucket cavity. 60 FINEMET ring cores have been tested to confirm their designed electrical properties. Some of these ring cores are then loaded, in steps, in a test cavity, which will further be used as the barrier-bucket cavity for the ESR.
* C. Dimopoulou et al., JACoW Proceedings of COOL 2007, Bad Kreuznach, Germany |
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| THPPP033 | New Developments for the Present and Future GSI Linacs | 3806 |
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| For more than three decades, GSI has successfully operated the Universal Linear Accelerator (UNILAC), providing ions from protons to uranium at energies from 3 to 11 MeV/u. The UNILAC will serve for a comparable period as injector for the upcoming FAIR facility which will ask for short pulses of high peak currents of heavy ions. The UNILAC Alvarez-type DTL has been in operation since the earliest days of the machine, and it needs to be replaced to assure reliable operation for FAIR. This new DTL will serve the needs of FAIR, while demands of high duty cycles of moderate currents of intermediate-mass ions will be met by construction of a dedicated superconducting cw-linac. FAIR requires additionally provision of primary protons for its pbar physics program. A dedicated proton linac is under design for that task. The contribution will present the future linacs to be operated at GSI. Finally we introduce a novel method to provide flat ion beams for injection into machines having flat injection acceptances. | ||
| THPPP036 | First Measurements of an Coupled CH Power Cavity for the FAIR Proton Injector | 3812 |
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| For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six CH cavities operated at 325 MHz. Each cavity will be powered by a 2.5 MW klystron. For the second acceleration unit from 11.5 MeV to 24.2 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH cavities. For this second tank technical and mechanical investigations have been performed to develop a complete technical concept for manufacturing. In Spring 2011, the construction of the first power prototype has started. The main components of this cavity were ready for measurements in fall 2011. At that time, the cavity was tested with a preliminary aluminum drift tube structure, which will allow precise frequency and field tuning. This paper will report on the recent technical developments and achievements. It will outline the main tuning and commissioning steps towards that novel type of proton DTL and it will show very promising results of the latest measurements. | ||
| THPPP074 | Chopping High Intensity Proton Beams Using a Pulsed Wien Filter | 3907 |
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Chopping high intensity beams at low energies poses substantial challenges. A novel ExB chopper system for proton beams of up to 200 mA at energies of 120 keV is being developed for the accelerator driven neutron source FRANZ*. It uses a Wien filter-type ExB configuration consisting of a static magnetic deflection field and a pulsed electric compensation field to deliver 100 ns beam pulses. The setup minimizes the risk of voltage breakdowns and provides secure beam dumping outside the transport line. In order to prevent beam aberrations and emittance growth careful matching of electric and magnetic deflection forces is required. Detailed numerical studies for the field design and their effects on beam transport were conducted. An H-type dipole magnet with special transverse and longitudinal pole contours was manufactured and combined with shielding tubes to shape the magnetic field. The electric field is driven by a HV pulse generator providing ±6 kV at a repetition rate of 250 kHz. Accurate layout of the deflector plates is required in order to tackle the issues of field quality, cooling and spark prevention. Transport simulations and beam deflection experiments are presented.
* U. Ratzinger et al., "The Driver Linac of the Neutron Source FRANZ," Proc. of IPAC2011, WEPS040, P. 2577 (2011). |
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